Sir,

We have grab type Barge unloaders erected for unloading iron ore cargo... The application is similar to Shipunloader which has hold drive and close drive of 250 kW rating working in tandom. The hold drive is provided with a separate converter unit with two six pulse thyristorised bridges in antiparallel combination operating at 415 V input voltage and 560 V output voltage, working in tandom with an IGBT inverter. Similar arrangement is made for a Close drive.

The problem faced is blowing of fuses which is also called commutation failure /inversion fault between dc links on outgoing of Converter (800 A) and incoming of Inverter (450A) during regeneration. DC links are independent in each drive.

Kindly suggest remedial action if any

Thnks and regads

Sangeeta ■